System and method for coating articles

ABSTRACT

A system and method is shown for coating an article, including a chamber that can be at least partially open to surrounding air to allow free flow of air through the chamber and recovery of vapor produced during a coating operation within the chamber. The chamber can include a support surface that is adapted to support the article during a coating process, and a coating device within the chamber can be adapted to selectively apply a coating of a fluorocarbon in a fluorinated solvent to at least a potion of an article supported on the support surface.

The teachings of the present application relate to methods and apparatusfor coating an article.

Hydrophobic coatings are useful for many applications, for example, toprevent rain from wetting-out or collecting on a windshield. Anotherapplication of hydrophobic coatings is in the field of laboratoryvessels. Laboratory vessels including chambers, microtiter plates,vials, flasks, test tubes, syringes, microcentrifuge tubes, pipettetips, selectively coated microscope slides, coverslips, films, poroussubstrates and assemblies comprising such devices are often used tohandle, measure, react, incubate, contain, store, restrain, isolate,and/or transport very precise and sometimes minute volumes of liquid,often biological samples. When samples are quantitatively analyzed, itcan be of critical importance that precise and representative amounts ofsample are transferred, or else inaccurate results are obtained. Due tothe different affinities of some materials to adhere to the walls of alaboratory vessel, qualitative analyses, such as concentrations ofmaterials may also be adversely affected if certain materials in asample selectively adhere to operational surfaces of the vessel walls.

Unfortunately, materials typically used in the manufacture of laboratoryvessels do not sufficiently repel many biological sample fluids nor dothey sufficiently resist the adherence of molecular constituents of sucha sample fluid. The sample fluids often wet the surface of the vesselcausing residual quantities of liquid sample to cling to an operationalsurface of the vessel when the sample is removed. In some cases,significant quantitative and/or qualitative errors result. It istherefore desirable to provide extremely hydrophobic coatings forlaboratory vessels which will reduce the wetting of the operationalsurfaces of the vessels and reduce clinging by even the most adherentsamples so that virtually no sample remains in the vessel when poured,ejected, or vacuumed therefrom.

Fluoroalkyl polymers have been used to produce oleophobic, hydrophobicmembrane surfaces that are not wetted by common organic solvents.Membranes coated with such polymers are disclosed in U.S. Pat. No.4,954,256 to Degen et al. These membranes have surface energies rangingfrom about 6 to about 15 dynes/cm but require a manufacturing procedurewhich involves soaking a membrane with a solution containingpolymerizable monomers, exposing the solution/wetted membrane to highdoses of ionizing radiation, and then washing the ionized membrane withorganic solvent to remove unreacted monomer. While no attempts are knownto coat laboratory vessels by such a procedure, it is expected thatdifficulties would arise as well as high cost in coating such vesselsbecause of the sheer bulk of the polymerizable solution to be irradiatedand problems with fully washing the coated vessel.

Methods of making disposable, one-time use laboratory vessels such aspipette tips can involve a substantial loss of costly solvent when acoating solution is used to form a hydrophobic coating. A need existsfor a process of coating laboratory vessels at a cost of a few cents perthousand with an insignificant loss of solvent.

The Renzacci Company of Italy manufactures perchloroethylene-basedcleaning machines that are widely recognized to be among the best in theindustry in terms of minimum solvent loss. But loaded with sixtythousand pipette tips in mono-filament mesh bags and using Renzacci'sstandard automated programs, these machines lose about five pounds ofFC84 (3M Company, St. Paul, Minn.) per cycle. This translates to solventconsumption costs of over $1.00 per thousand tips. Higher boiling pointfluorocarbon solvents have lower loss rates, but the solvent expense isabout the same due to their higher cost per pound.

The Renzacci standard automated program partially fills acleaning/coating tank of approximately one-half cubic meter with solventat ambient temperature from a solvent reservoir. Articles in the tankare then tumbled in the solvent for several minutes, followed by drain,spin, and spin-rinse cycles. With continuing tumbling, a heat pump and asupplementary heat source (electric, steam, etc.) heat air blown throughthe tank, while passing air returns from the tank over chilledcondensation coils where solvent vapor is liquified and returned to thereservoir. Water is circulated through the heat pump system to removeexcess heat. However, the temperature in the tank can still rise to over50° C. and the reservoir temperature can rise to more than 30° C. At theend of the process cycle, heating is discontinued and the tank andreservoir are cooled to about 30° C. When the tank door is opened toremove the cleaned/coating articles, a small blower draws air out of thetank through a carbon filter in order to reduce the odor of remainingperchloroethylene solvent. Unfortunately, at 30° C., the solvent FC84has a vapor pressure of over one fifth atmosphere, and the half cubicmeter tank volume contains about two pounds of solvent as dense vapor(about 14 times that of air), even without agitation. Opening the tankdoor results in the immediate loss of this material.

SUMMARY

According to various embodiments, a system for coating an article isprovided that comprises a chamber at least partially open to asurrounding environment to enable a flow of environmental gas or airthrough the chamber and recovery of vapor produced during a coatingoperation within the chamber. The chamber can be provided with at leastone support surface that can be adapted to support the article during acoating process. At least one coating device can be provided within thechamber and can be adapted to selectively apply a solution of afluorocarbon in a fluorinated solvent to at least a portion of anarticle supported on the support surface, to form a coating on at leastthe portion. The at least one coating device in the chamber can beadapted to spray a solution of a fluorocarbon in a fluorinated solventon at least a portion of an article supported on the support surface.According to various embodiments, the at least one coating device can beadapted to dip at least a portion of an article into a solutioncomprising a fluorocarbon in a fluorinated solvent. The coating deviceaccording to various embodiments can be adapted to draw a solution offluorocarbon in a fluorinated solvent over and in contact with at leasta portion of an article supported on the support surface, for example,using a negative pressure or suction created within the chamber. It isto be understood that the solution of fluorocarbon in fluorinatedsolvent described herein can instead comprise a mixture, suspension,emulsion, or other composition of fluorocarbon in a fluorinated solvent,but is herein referred to as a solution or composition.

A method of treating an article according to various embodimentscomprises providing a chamber that is at least partially open to asurrounding environment, for example, to surrounding air, to enable afree flow of gas or air through the chamber, wherein the chambercomprises a support surface therein. An article can be supported on thesupport surface to be treated within the chamber. A free flow of air canbe maintained through the chamber and around the article supported onthe support surface, and the article can be treated by selectivelyexposing part or all of the article to a fluorocarbon in the fluorinatedsolvent. According to various embodiments, the method can comprisecoating a sheet, film, roll, or web of material, for example, as it isunrolled off of a supporting roller. The coated sheet, film, roll, orweb can be dried and/or cured and then rolled up onto the same or adifferent supporting roller inside or outside of the chamber.

According to various embodiments, a method of applying a coatingcomposition can be provided that comprises providing an array ofindividually removable lab vessels or other articles, and selectivelyapplying a coating composition of a fluorocarbon in a fluorinatedsolvent to one or more of the array of lab vessels or articles to coat aportion or the entirety of the one or more lab vessels or articles ofthe array.

According to various embodiments, an apparatus for applying a coatingcomposition can be provided that comprises means for supporting an arrayof lab vessels or other articles, with each lab vessel or other articlebeing individually removable from the array, and means for selectivelyapplying a coating composition of a fluorocarbon in a fluorinatedsolvent to one or more of the lab vessels or other articles to coat aportion or the entirety of the lab vessels or other articles of thearray.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are intended to provide a further explanation of the presentteachings.

BRIEF DESCRIPTION OF THE DRAWINGS

The skilled artisan will understand that the drawings described beloware for illustration purposes only. The drawings are not intended tolimit the scope of the present teachings in any way.

FIG. 1 illustrates a schematic diagram of a system for coating anarticle according to various embodiments; and

FIG. 2 illustrates a side view of a system including a support surfaceand an article to be coated in the form of a rolled web of material.

DESCRIPTION OF VARIOUS EMBODIMENTS

According to various embodiments, a system for coating an article can beprovided. The system can include a chamber that is at least partiallyopen to the surrounding environment to enable free flow of environmentalgas or air through the chamber and recovery of vapor produced during acoating operation within the chamber. As shown in FIG. 1, the system 100can include a chamber 20 that is at least partially open through anopening 22 to the surrounding ambient air 24. Baffles or partitions 23,25 can be provided across the opening 22 to provide further control ofatmospheric exchange between the interior of chamber 20 and thesurrounding ambient air 24. The chamber 20 can include various devicesand/or stations such as a coating device 40, a reservoir station 50, adrying station 60, and a docking station 70. An article 30 to be coatedcan be movable between the various stations, for example, movable on aconveyor belt or by a robotic handling device. The chamber 20 can be influid communication with an exhaust manifold 26 that can at leastpartially surround the chamber 20, and that can provide a pathway forair and vapor produced within the chamber 20, during a coatingoperation, to exit through an exit duct 28 and into a solvent recoverysystem 80.

Various devices or means can be provided for moving the article 30within the chamber 20. Although not shown in FIG. 1, a robotic assemblyor other conveyor means could be provided for initially moving thearticle 30 to a position to be docked prior to treatment by the coatingdevice 40. The robotic assembly or conveyor device can then move thearticle 30 and/or coating device 40 to the reservoir station 50 duringthe coating process. The robotic assembly or conveyor can then move thearticle 30 to the drying station 60 and return the coating device to itsoriginal position. After the article 30 has been dried at the dryingstation 60, the article can be moved to the docking station 70, fromwhich the coated article can then be retrieved for removal from thechamber 20. The robotic assembly can comprise a robotic arm mechanismthat is adapted to grasp the article or array of articles and move thearticle or articles between the various stations and/or devices.Alternatively, the robotic assembly can comprise a conveyor belt adaptedto move the article or articles between the various stations and/ordevices within the chamber 20. An alternative arrangement can compriseprotective sleeves or other protective device for allowing a user toreach into the chamber 20 to manipulate the article or articles betweenthe various devices and/or stations, while avoiding contact with thecoating composition and/or fumes produced during the coating process.

The open configuration of chamber 20 allows for an article or articles30 to be placed in or removed from the chamber 20 through the opening22, while at the same time maintaining an air flow from ambient air 24through the chamber opening 22 and past baffles or partitions 23, 25,and past the article or articles 30, as the article or articles aremoved between the various devices and stations, for example, between thecoating device 40, reservoir station 50, drying station 60, and dockingstation 70.

Air that is drawn through the chamber 20 during a coating operationcollects any solvent that remains in the form of a vapor after thecoating operation and draws the air and solvent vapor through theexhaust manifold 26, the exhaust duct 28, and into the solvent recoverysystem 80. The solvent recovery system 80 can include a chiller thatlowers the temperature so as to cause condensation of the solvent into aliquid form that can be easily recovered. An air pump 90 can draw theair from the solvent recovery system after recovery of the solventvapor, with the air being directed through a downstream duct 82, andthrough a return manifold 84 back into the chamber 20. The constantcirculation of air into the chamber 20 and out through exhaust manifold26 to the solvent recovery system 80 ensures that any solvent vaporproduced during the coating operation within chamber 20 can berecovered.

According to various embodiments, an article or articles 30 withinchamber 20 can be supported and docked to the coating device 40, andthen be moved to the reservoir station 50. At the reservoir station 50,the article or articles 30 can be filled with a coating composition fromthe reservoir station 50, and then the fluid can be withdrawn from thearticles leaving only the desired coating behind on the articles.According to various embodiments, the article or articles can be dippedinto and then removed from a coating composition at the reservoirstation 50.

As discussed in U.S. Pat. No. 6,767,587, which is herein incorporated inits entirety by reference, an extremely hydrophobic coating can beformed on the surface of an article. The coating can comprise, forexample, the reaction product of a reactant containing a terminaltrifluoromethyl group. Articles such as laboratory vessels to be coatedaccording to a process of the present teachings, can comprise, forexample, plastic, metal, or glass, and can include any of the tubes,vials, slides, microcentrifuge tubes, test tubes, pipettes, pipettetips, or other vessels described in U.S. Pat. No. 6,767,587. Exemplarymaterials of laboratory vessels that can be coated according to variousembodiments can include polypropylene, polyethylene,polyethyleneterephthalate, polystyrene, polycarbonate, and cellulosicmaterials. According to various embodiments, the articles can compriseplastics such as polytetrafluoroethylene or other fluorinated polymers.Any of many different coatings of a fluorocarbon in a fluorinatedsolvent, such as those disclosed in U.S. Pat. No. 6,767,587, can beapplied to the article or articles at the reservoir station 50. Thearticles can then be moved to the drying station 60 while thesurrounding ambient air 24 is drawn through the opening 22 into chamber20, past the articles at the drying station, and into exhaust manifold26. After the articles have been dried they can then be moved to thedocking station 70 for ready removal from the chamber 20.

According to various embodiments, the article 30 docked to coatingdevice 40 can be moved to the reservoir station 50 and sprayed with afluid from the reservoir station 50 to provide a desired coating. Thespraying can be performed by one or more nozzles if provided as part ofthe coating device, and the coating composition can be directed toselected areas of the article or articles, and then the article orarticles can be moved to the drying station 60. The coating device canbe returned to its original position, ready to perform a spraying orcoating operation on additional articles. After drying at the dryingstation 60, the article or articles can be moved by a robotic assembly,or by being placed on a conveyor belt. Placement can occur manuallyusing gloves, or through other handling means, to achieve placement atthe docking station 70 from which the article or articles can beretrieved automatically or manually for removal from the chamber 20.

According to various embodiments, the article 30 can be coated by beingdipped, at least partially, into a coating composition provided at thereservoir station 50, to selectively apply a coating to the entirety ofor to only a portion of the article. After such a dipping operation, thearticle or articles can then be moved to the drying station 60 and thento the docking station 70.

According to various embodiments, an air pump 90 can be provideddownstream of the solvent recovery system 80 and can be used to create asuction or pressure differential that draws ambient air 24 through thechamber, past the coating station, through the exhaust manifold 26, andinto the solvent recovery system 80. After solvent in vapor form hasbeen removed from the air and vapor mixture drawn in from the chamber20, the clean air can then be directed through the return duct 82 andreturn manifold 84, back into the chamber 20.

According to various embodiments, the article 30 within chamber 20 canbe supported on a support surface that includes openings therethrough incommunication with the exhaust manifold 26, such that a pressuredifferential created between the chamber and the solvent recovery system80 results in ambient air moving past the article on the supportsurface. The moving air can carry with it solvent vapor generated fromthe coating operation and direct the solvent vapor into the solventrecovery system 80.

According to various embodiments, a method of applying a coating to anarticle can comprise coating an array of individually removable labvessels or other articles, for example, an array of centrifuge tubes ortest tubes disposed in a rack. A coating composition, for example, asolution of fluorocarbon in a fluorinated solvent, can be selectivelyapplied to one or more of the lab vessels of the array to coat a portionor the entirety of the one or more lab vessels within the chamber 20.The array of lab vessels or other articles can be provided in an arraysupport comprising a plurality of openings, each sized to accommodate arespective one of the individually removable lab vessels, for example, arack. The application of the coating composition to at least a portionof one or more articles supported within the array can be achieved byselectively inserting a spray nozzle, or a plurality of spray nozzles,partially or fully into selected ones or all of the articles within thearray, or by directing spray from one or more spray nozzles at thedesired portions of the one or more articles within the array.

The coating operation performed within chamber 20 can be conducted whilemaintaining a constant flow of air through the chamber and into theexhaust manifold 26, or, alternatively, the air flow can be regulated orchanged before, during, and/or after a coating operation.

According to various embodiments, the article to be coated can be amoving web of material, a continuous web of material, or a moving andcontinuous web of material. According to various methods, the web can becoated with a system such as that illustrated in FIG. 2. The entiresystem shown in FIG. 2 can be incorporated and housed inside a chamber,for example, chamber 20 shown in FIG. 1. Alternatively, the supplyand/or take-up rolls for the web of material can be located outside of acoating chamber while the coating composition supply nozzle and supportsurface are located within a chamber.

As illustrated in FIG. 2, a web of material 200 can be supplied from asupply roll 202 and taken-up by a take-up roll 204. The web 200 can movein the direction shown by arrow 206 over a support roller 208 and over asupport surface 210. A coating composition supply nozzle 212 can bearranged on a side of the web 200 opposite the side supported by supportsurface 210. The coating composition supply nozzle 212 can be connectedto a supply or source of a coating composition and can apply a coatingcomposition to the top surface of web 200, for example, while the web200 is moved in the direction shown by arrow 206. Alternatively,portions of the web can be coated stepwise in between advancing motionsof the web, for example, while the web is held momentarily stationary.The support surface 210 can comprise a porous surface or otherwiseinclude holes or apertures through which excess coating composition andcoating composition solvent can be drawn and directed to a vaporrecovery system 214. After passing over the support surface 210, thecoated web can then pass over a second support roller 216 and around aheated curing roller 218. After contacting the heated curing roller 218,the coated web can be guided by another support roller 220 and directedtoward a pair of nip rollers 222 before being taken-up by the take-uproller 204.

According to various embodiments, if the article to be coated cancomprise a web of material, the web of material can comprise a paperweb, a plastic web, a foil web, a textile web, a woven web, anelastomeric web, or the like. In some embodiments, a web is coated thatcan comprise a roll of carpet or a roll of fabric. In some embodiments,unrolled fragments or sections of a rolled material can be passedthrough a coating station adapted to recover fluorinated solvent vapor.

Other embodiments of the present invention will be apparent to thoseskilled in the art from consideration of the present specification andpractice of the present teachings disclosed herein. It is intended thatthe present specification and examples be considered as exemplary only.

1. A system for coating an article, comprising: an exhaust manifold; achamber in direct fluid communication with the exhaust manifold, thechamber having openings in at least one wall thereof in direct fluidcommunication with surrounding ambient air to enable (1) a constantcirculation of ambient air through the chamber during a coatingoperation within the chamber, and (2) recovery of vapor produced duringa coating operation within the chamber; a support surface that isdisposed in the chamber and adapted to support an article during acoating process; a solvent recovery system in direct fluid communicationwith the exhaust manifold through an exhaust duct and configured torecover vapor produced in the chamber while a coating operation is beingperformed, the solvent recovery system consisting of a chillerconfigured to cause condensation of solvent vapor into solvent in liquidform; an air pump configuration to draw air and solvent vapor throughthe exhaust manifold and exhaust duct into the solvent recovery system;a return manifold in fluid communication with the chamber; a return ductdisposed between the solvent recovery system and the return manifold andin fluid communication with both and configured to return only air andany uncondensed solvent vapor directly to the chamber through the returnmanifold; a supply of fluorocarbon in a fluorinated solvent; and acoating device in communication with the supply of fluorocarbon in afluorinated solvent, the coating device configured to apply a coating ofthe fluorocarbon in a fluorinated solvent to at least a portion of thearticle supported on the support surface, while a constant flow of airis maintained and circulated through the chamber.
 2. The system of claim1, wherein: the coating device is adapted to draw the fluorocarbon in afluorinated solvent past at least a portion of an article supported onthe support surface using a pressure differential created within thechamber.
 3. The system of claim 2, wherein the pressure differential isa suction.
 4. The system of claim 1, wherein the support surfaceincludes openings therethrough in communication with an exit port fromthe chamber, the exit port adapted to receive a pressure less than apressure within the chamber, thereby providing a suction flow path forvapor produced within the chamber during a coating operation.
 5. Thesystem of claim 4, further comprising: a pump in fluid communicationwith the exit port.
 6. The system of claim 1, further comprising anarticle at least partially supported by the support surface, wherein thearticle comprises a roll of material.
 7. The system of claim 1, whereinthe air pump is adapted to pull air from the solvent recovery system anddirect air to the return manifold.
 8. The system of claim 1, wherein theair pump is configured to maintain a constant circulation of air throughthe chamber.
 9. The system of claim 1, further comprising a movingdevice configured to move the article from the support surface to adrying surface.
 10. The system of claim 9, wherein the moving devicecomprises a conveyor belt.
 11. The system of claim 9, wherein the movingdevice comprises a robotic assembly.
 12. The system of claim 1, furthercomprising a robotic assembly that is configured to move the article tovarious stations and devices within the chamber.
 13. The system of claim1, further comprising a conveyor belt that is configured to move thearticle to various stations and devices within the chamber.